The present invention relates to a protocol for a power supply unit (PSU) controller.
In a rack enclosure comprising a backplane across which a plurality of devices, for example, storage disks communicate across a bus, for example, a SCSI bus, one or more power supply units are frequently used to supply power in the form of one or more voltage supply rails to the backplane for use by the devices. With the increasing complexity of configuration of rack enclosures, their continued operation can become more critical and so it becomes important not alone to diagnose faults when they have occurred but also to determine when faults may occur and what their cause might be.
The present invention seeks to mitigate the problems of detecting and diagnosing problems which may occur in a rack enclosure power supply unit.
According to the present invention there is provided a power supply unit controller for a rack enclosure in which a plurality of devices communicate via a backplane, said controller comprising:
means for reading at least one signal indicative of an output supply level being provided to said backplane by a power supply unit associated with said power supply unit controller;
memory for storing at least one value associated with a respective one of the at least one signal, at least one scaling value associated with a respective one of the at least one signal and dependent on said power supply unit, and a power supply unit serial number;
communicating means, responsive to a request from one of said devices, for a returning a state of said associated power supply unit to said requesting device, said state including a combination of:
a summary of the current status of the power supply unit,
said at least one value,
said at least one scaling value, and
said power supply unit serial number,
according to said device request.
The power supply unit controller of the present invention stores scaling factors dependent on the supply levels supplied by the power supply unit associated with the controller. These can be retrieved by, for example, a higher level processor monitoring environmental conditions in an entire rack enclosure. Using the scaling factor with its associated value read from the power supply unit by the power supply unit controller, the software in the higher level processor and the power supply unit controller itself can be made independent of the power supply unit itself. Furthermore, storing the power supply unit serial number in the controller enables messages identifying the specify power supply unit to be relayed to an operator, who can then correlate the message with a label on the power supply unit indicating the power supply unit serial number. Clearly not all information is required by a higher level processor in response to every request, and so the request can be formatted to condition the amount of information returned by the power supply unit controller.
According to a second aspect of the invention there is provided a rack enclosure including a backplane, at least one power supply unit connected to and adapted to supply power to said backplane, each associated with a respective power supply unit controller according to the invention, and a plurality of devices receiving power from said backplane, at least one of said devices adapted to communicate with the at least one power supply unit controller.